any of several cultivated Eurasian chrysanthemums, such as Chrysanthemum coccineum and C. roseum, with white, pink, red, or purple flowers
2.
any insecticide prepared from the dried flowers of any of these plants, esp C. roseum
Word origin
C16: via Latin from Greek purethron feverfew, probably from puretos fever; see pyretic
pyrethrum in American English
(paɪˈrɛθrəm; paɪˈriθrəm)
noun
1.
a perennial plant (Chrysanthemum coccineum) of the composite family, widely grown for the white, pink, red, or purple flower heads
2.
an insecticide made from the dried flower heads of several Old World chrysanthemums, esp. a species (Chrysanthemum cinerariaefolium) now grown extensively in the U.S.